Description: 密度是物质或物体的一种物理特性，表示了其体积与质量的关系。密度越大，单位体积的质量就越大。物体的平均密度是其总质量除以总体积。在国际单位制（SI）下，其单位是千克/立方米（kg/m³）。

在太阳周围的银河系区域内，密度的数值可从星际气体的约10^-20 kg/m³变化到中子星内部的超过10¹⁷ kg/m³。

地球上常见的密度数值介于这两个极端之间，例如铁的密度约为7800 kg/m³，水的密度约为1000 kg/m³，在海平面附近、围绕着我们的空气密度略高于1 kg/m³。

宇宙不仅包括恒星、行星和星系中的气体，还包括星系之间和星系团之间相对空旷的空间。因此，宇宙中物质的平均密度约为10^-27 kg/m³。

Related Terms:

• 质量
• 中子星
• 星际介质

Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

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